• 약학회지
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• 제38권5호
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• pp.511-515
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• 1994

We examined the inhibitory activity of (1,3-dioxolan-2-yl and 1,3-dioxan-2-yl)methylaminium derivatives(A; 1-8) against acetylcholinesterase. Derivatives of six-membered 1,3-dioxane exhibited more potent inhibitory effect than corresponding 5-membered 1,3-dioxolanes. The presence of methyl group at C4 position of dioxane ring was effective to increase the inhibitory potency of heterocyclic analogues. The activity of N-phenacyl-aminiums was greater than that of N,N,N-trimethyl-aminiums. In general, the terminal methyl group on 1,3-dioxane ring and the phenacyl group in ammonium compound A were assumed to be important factors to enhance the inhibitory action.

• Toxicological Research
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• 제16권4호
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• pp.275-284
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• 2000

The organ culture model of the whole mammary gland has many advantages for the study of branching morphogenesis and biological characteristics, including tumorigenesis. Prior to whole gland organ culture, rats were treated with 7,12-dimethylbenz[a]anthracene (DMBA) or N-methyl-N-nitrosourea (MNU) for one week. The tramdorming effect and the morphological changes were assessed by the whole mount preparations and histopathological examination in terminal end buds (TEB), terminal ducts (TD), alveolar buds (AB), alveolar lobules (AL) and hyperplastic alveolar nodules (HAN) of the mammary gland. Grossfindings of the mammary glands at dissection were higher branching morphogenesis and larger volume in carcinogen-treated groups than in carcinogen-non-treated groups. Results of the whole mount method were coincided with those of the histopathological observations. Circular TEB, normally maintained AB, AL, and high cellular density were more frequently observed in carcinogen-treated groups than in carcinogen-nan-treated groups. Histopathologically, as a preneoplastic marker, HAN was maintained only in mammary organ culture of the carcinogen-treated groups. These findings suggest that in vivo trans-formation effects by carcinogens persisted during the mammary organ culture. These results were more characteristic in DMBA than in MNU-treated group. Ducts and terminal ducts appeared to have lost morphology during their growths in case of without diethylstilbestrol (DES). The fact that in vitro organ culture without DES was resulted in abnormal ductular morphogenesis confirms that DES is a physiological regulator of ductular epithelial cell growth.

• 미생물학회지
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• 제40권4호
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• pp.257-262
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• 2004

ErmSF는 235 rRNA에 존재하는 $A_{2058}$에 이중메틸화(dimethylation)시킴으로써 항생제가 부착되는 것을 억제하여 미생물에게 MLS (macrolide-lincosamide-streptogramin B)항생제에 대하여 내성을 나타내게 하는 ERM계열 단백질(Erm family protein)중의 하나이다. 다른 ERM 단백질과는 달리 ErmSF는 상당히 긴 N-말단부위 (N-terminal end region, NTER)를 가지고 있고 이겻은 RNA와 잘 결합하는 것으로 알려진 arginine이 약 $25\%$를 구성 하고 있다. ErmSF로부터 점차적으로 NTER을 절단하면서 절단된 단백질의 활성을in vivo에서 검색하였다. 다른 변이단백질과는 달리 R60번째까지 제거된 변이단백질은 활성이 많이 소실된 것을 in vivo상에서 관찰하였다. 이 단백질을 대량생산하여 정제하고 in vivo상에서 그 활성을 검색한 결과 wild type 단백질에 비해 약 $98\%$의 활성이 소실된 것을 밝혔다. 이러한 사실은 R60이 메틸화되는 아데닌 (methylatable adenine)의 근처에 존재하는 RNA와 작용하여 메틸화되는 아데닌이 활성화부위에 적절히 위치하도록 하는 역할을 담당한다는 것을 암시하고 있다.

• 대한화학회지
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• 제34권2호
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• pp.130-135
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• 1990

Z-3-파라-톨리치오-4-니트로-3-헥센의 결정은 단사정계에 속하며 a = 13.756 (3), b = 9.310(4), c = 21.305(3) $\AA$, $\beta = 95.0_{\circ}$이며 단위세포안에 8개의 분자가 있으며 2.0$\sigma$(I) 보다 큰 강도를 가진 2935개의 회절반점에 대하여 계단식 대각 최서자승법에 의하여 정밀화된 최종 R값은 0.085이다. 직접법에 의하여 구조를 풀었으며 C-H결합길이와 메칠기는 길이를 고정시켜 이상적인 기하학적구조에 맞도록 하여 계산을 정밀화하였다. 두 분자 A와 B는 끝의 두 에칠기를 제외하고는 거의 유사한 구조를 갖고 있다. 니트로기를 포함한 에틸렌 모양의 골격은 메칠벤젠기에 거의 수직으로 되어 있으며 두 에틸기는 시스-형 구조를 가지고 있으나 끝부분의 메칠기는 A분자에서는 그의 골격에 대해 서로 반대방향으로 향하고 있고 B분자는 같은 방향으로 향하고 있다. 결정내 분자들은 비결합성 van der Waals힘으로 쌓여져 있다.

• Journal of Photoscience
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• 제9권2호
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• pp.178-181
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• 2002

Pyropheophorbide and pheophorbide-photosensitizers as chlorin analogues are promising new compounds for PDT because the chlorin analogues are activated with much longer red light at > 670nm and produce less long-term normal tissue phototoxicity than Photofrin. The various chlorin derivatives can be obtained by moditying peripheral substituted group among which meso-H, vinyl group and exocyclic ring are the most active positions. These characteristics prompted us to introduce various groups for constructing modified pyropheophorbide and pheophorbide a compounds. A stereospecific introduction of various double bonds at 3-position was performed to methylpheophorbide a to give a long hydrophobic moiety and cyclic derivatives. Chlorin-C$_{60}$ dyad and chlorin- $C_{60}$-porphyrin triad also were easily prepared by the reaction of terminal aldehyde of methyl pyropheophorbide a. For the reaction on meso $\delta$-position bromination and Vismeier formylation can occur. N,N-dimethylaminoacrolein also reacted on $\delta$-position and was cyclized to isobacteriochlorin, but other modification has not been succeeded. Exocyclic keto function was also modified to give purpurin derivatives, bicyclic and spiro compounds. In this presentation we report a series of modified pyropheophorbide and pheophorbide a derivatives.s.

• 한국미생물·생명공학회지
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• 제18권4호
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• pp.338-343
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• 1990

Streptomyces sp. DMCJ-49 균주의 배양액으로부터 분리된 $\alpha$-amylase 저해물질 MB4-03은 구조상 질소원자와 methyl기를 포함하는 일종의 직선형 Alpha(1-4) 결합으로 연결된 glucose의 변형된 oligomer 형태로서 구성 단당류는 12 정도로 추정된다.

• 한국결정학회:학술대회논문집
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• 한국결정학회 2003년도 춘계학술연구발표회
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• pp.17-17
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• 2003

tRNA (m¹ G37) methyltransferase (TrmD) catalyze s the trans for of a methyl group from S-adenosyl-L-methionine (AdoMet) to G/sup 37/ within a subset of bacterial tRNA species, which have a residue G at 36th position. The modified guanosine is adjacent to and 3' of the anticodon and is essential for the maintenance of the correct reading frame during translation. We have determined the first crystal structure of TrmD from Haemophilus influenzae, as a binary complex with either AdoMet or S-adenosyl-L-homocysteine (AdoHcy), as a ternary complex with AdoHcy/phosphate, and as an apo form. The structure indicates that TrmD functions as a dimer (Figure 1). It also suggests the binding mode of G/sup 36/G/sup 37/ in the active site of TrmD and catalytic mechanism. The N-terminal domain has a trefoil knot, in which AdoMet or AdoHcy is bound in a novel, bent conformation. The C-terminal domain shows a structural similarity to DNA binding domain of trp or tot repressor. We propose a plausible model for the TrmD₂-tRNA₂ complex, which provides insights into recognition of the general tRNA structure by TrmD (Figure 2).

• Macromolecular Research
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• 제17권8호
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• pp.557-562
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• 2009

The free radical polymerization of styrene was initiated with azobis(isobutyronitrile) in the presence of benzene sulfonyl chloride. Analysis of the terminal structures of the obtained polystyrene with $^1H$ NMR spectroscopy revealed the presence of a phenyl sulfonyl group at the ${\alpha}$-end and a chlorine atom at the ${\omega}$-end of each polystyrene chain. The terminal chlorine atom in the polystyrene chains was further confirmed through atom transfer radical polymerization (ATRP) of styrene and methyl acrylate using the obtained polystyrenes as macroinitiators and CuCl/2,2'-bipyridine as the catalyst system. GPC traces of the products obtained in ATRP at different reaction times were clearly shifted to higher molecular weight direction, indicating that nearly all the macroinitiator chains initiated ATRP of the second monomers. In addition, the number-average molecular weights of the polystyrenes increased directly proportional to the monomer conversions, and agreed well with the theoretical ones.

• 대한의생명과학회지
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• 제16권1호
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• pp.25-32
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• 2010

Sprague-Dawley(SD) rats were orally administered with $N^G$-nitro-L-arginine methyl ester(L-NAME) which inhibits or blocks the production of nitric oxide from L-arginine in vascular endothelial cells and vessel tissue to statistically examine the effects of nitric oxide on some physiological changes such as blood pressure and heart rate, and to confirm the apoptosis induced by the suppressed nitric oxide activity in some related organs under light microscope. Systolic blood pressure significantly increased 28.5% by the chronic treatment of L-NAME for 8 weeks (P<0.001), no significant difference, however, was observed in heart rate between the control group and the L-NAME-treated group regardless of their age. Hematoxylin-eosin staining showed some histological alterations only in kidney among the examined organs; heart, liver, pancreas, and adrenal gland from the L-NAME-treated group. TUNEL (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling) test showed a strong positive reaction, representing that the chronic treatment of L-NAME facilitates apoptosis, in the cortex and medulla of kidney, but not any significance detectable in the other organs. These results conclude that chronic treatment of L-NAME significantly increases blood pressure, and that the followed inhibition of nitric oxide synthesis occurs a typical inducement of apoptosis in kidney.

• Bulletin of the Korean Chemical Society
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• 제15권3호
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• pp.198-204
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• 1994

Chemical shifts in aqueous sodium dodecylsulfate(SDS) micellar solution solublizing phenol, catechol, resorcinol, hydroquinone have been measured to investigate solubilization properties. Proton nuclear magnetic resonance frequencies of solubilizates as well as those of the ${\alpha}$-methylene, middle methylene and terminal methyl of SDS shift linearly as a function of solubilizate concentration. From the plots of observed chemical shift (v) vs solubilizate concentration, slope (a) and solubilizate free chemical shift ($v_0$) are obtained. They are very informative to solubilization site of the systems. Catechol and phenol solubilized SDS and catechol solubilized dodecylpyridinium chloride(DPC), dodecyltrimethylammonium bromide(DTAB) systems are studied using the same method to compare head group effect and middle methylene proton signal splitting. It is proposed that phenol and catechol are inserted into micellar interior and the number of methylenes assigned to the higher field peaks is 5.0${\pm}$0.5.